linux-kernel - Re: [PATCH v5 0/9] ovl: Enable support for casefold layers

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Message-ID: <CAOQ4uxjf6S7xX+LiMaxoz7Rg03jU1-4A4o3FZ_Hi8z6EyEc7PQ@mail.gmail.com>
Date: Sun, 17 Aug 2025 17:03:50 +0200
From: Amir Goldstein <amir73il@...il.com>
To: André Almeida <andrealmeid@...lia.com>
Cc: Miklos Szeredi <miklos@...redi.hu>, Theodore Tso <tytso@....edu>, linux-unionfs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	kernel-dev@...lia.com, Gabriel Krisman Bertazi <krisman@...nel.org>
Subject: Re: [PATCH v5 0/9] ovl: Enable support for casefold layers

On Fri, Aug 15, 2025 at 3:50 PM Amir Goldstein <amir73il@...il.com> wrote:
>
> On Fri, Aug 15, 2025 at 3:34 PM André Almeida <andrealmeid@...lia.com> wrote:
> >
> > Hi Amir,
> >
> > On 8/14/25 21:06, Amir Goldstein wrote:
> > > On Thu, Aug 14, 2025 at 7:30 PM André Almeida <andrealmeid@...lia.com> wrote:
> > >> Em 14/08/2025 14:22, André Almeida escreveu:
> > >>> Hi all,
> > >>>
> > >>> We would like to support the usage of casefold layers with overlayfs to
> > >>> be used with container tools. This use case requires a simple setup,
> > >>> where every layer will have the same encoding setting (i.e. Unicode
> > >>> version and flags), using one upper and one lower layer.
> > >>>
> > >> Amir,
> > >>
> > >> I tried to run your xfstest for casefolded ovl[1] but I can see that it
> > >> still requires some work. I tried to fix some of the TODO's but I didn't
> > >> managed to mkfs the base fs with casefold enabled...
> > > When you write mkfs the base fs, I suspect that you are running
> > > check -overlay or something.
> > >
> > > This is not how this test should be run.
> > > It should run as a normal test on ext4 or any other fs  that supports casefold.
> > >
> > > When you run check -g casefold, the generic test generic/556 will
> > > be run if the test fs supports casefold (e.g. ext4).
> > >
> > > The new added test belongs to the same group and should run
> > > if you run check -g casefold if the test fs supports casefold (e.g. ext4).
> > >
> > I see, I used `check -overlay` indeed, thanks!
> >
>
> Yeh that's a bit confusing I'll admit.
> It's an overlayfs test that "does not run on overlayfs"
> but requires extra overlayfs:
>
> _exclude_fs overlay
> _require_extra_fs overlay
>
> Because it does the overlayfs mount itself.
> That's the easiest way to test features (e.g. casefold) in basefs
>

I tried to run the new test, which is able to mount an overlayfs
with layers with disabled casefolding with kernel 6.17-rc1.

It does not even succeed in passing this simple test with
your patches, so something is clearly off.

> You should also run check -overlay -g overlay/quick,
> but that's only to verify your patches did not regress any
> non-casefolded test.
>
>

My tests also indicate that there are several regressions, so your patches
must have changed code paths that should not have been changed.

Thanks,
Amir.